U.S. patent application number 10/393435 was filed with the patent office on 2003-11-27 for substrate for liquid crystal display device, liquid crystal display device provided with the same,manufacturing method of the same, and manufacturing apparatus of the same.
This patent application is currently assigned to FUJITSU DISPLAY TECHNOLOGIES CORPORATION. Invention is credited to Murata, Satoshi, Suzuki, Hidehiko.
Application Number | 20030218713 10/393435 |
Document ID | / |
Family ID | 28456283 |
Filed Date | 2003-11-27 |
United States Patent
Application |
20030218713 |
Kind Code |
A1 |
Suzuki, Hidehiko ; et
al. |
November 27, 2003 |
Substrate for liquid crystal display device, liquid crystal display
device provided with the same,manufacturing method of the same, and
manufacturing apparatus of the same
Abstract
The invention relates to a substrate for a liquid crystal
display device used for a display part of an information equipment,
a liquid crystal display device provided with the same, a
manufacturing method of the same, and a manufacturing apparatus of
the same, and has an object to provide a substrate for a liquid
crystal display device in which a manufacturing process can be
simplified and a frame part can be narrowed, a liquid crystal
display device provided with the same, a manufacturing method of
the same, and a manufacturing apparatus of the same. A liquid
crystal display device includes a TFT substrate and a CF substrate
disposed to be opposite to each other, a liquid crystal sealed
between the two substrates, a light shielding film formed on an
outer peripheral part of the CF substrate, a display region defined
by the light shielding film, metal layers formed on an outer
peripheral part of the TFT substrate at a side of the liquid
crystal and having a width of 0.1 mm or less, and a photo-curing
sealing agent coated on the outer peripheral part to overlap with
the light shielding film when viewed in a vertical direction
relative to a substrate surface and provided with a light
irradiated region overlapping with the metal layers.
Inventors: |
Suzuki, Hidehiko; (Kawasaki,
JP) ; Murata, Satoshi; (Kawasaki, JP) |
Correspondence
Address: |
GREER, BURNS & CRAIN
300 S WACKER DR
25TH FLOOR
CHICAGO
IL
60606
US
|
Assignee: |
FUJITSU DISPLAY TECHNOLOGIES
CORPORATION
|
Family ID: |
28456283 |
Appl. No.: |
10/393435 |
Filed: |
March 20, 2003 |
Current U.S.
Class: |
349/156 |
Current CPC
Class: |
G02F 1/1339 20130101;
G02F 1/133512 20130101 |
Class at
Publication: |
349/156 |
International
Class: |
G02F 001/1339 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2002 |
JP |
2002-088643 |
Feb 18, 2003 |
JP |
2003-040231 |
Claims
What is claimed is:
1. A liquid crystal display device, comprising: two substrates
disposed to be opposite to each other; a liquid crystal sealed
between the two substrates; a light shielding film formed on an
outer peripheral part of one of the substrates to intercept light;
a display region defined by the light shielding film; a metal layer
formed on an outer peripheral part of the other substrate at a side
of the liquid crystal and having a width of 0.1 mm or less; and a
photo-curing sealing agent coated on the outer peripheral part to
overlap with the light shielding film when viewed in a vertical
direction relative to a substrate surface and provided with a light
irradiated region overlapping with the metal layer.
2. A liquid crystal display device according to claim 1, wherein
the other substrate includes a light shielding layer for
intercepting light within a region from an end part of the display
region to an end part of the sealing agent at a side of the display
region.
3. A liquid crystal display device according to claim 2, wherein
the light shielding layer includes an overlap region having an
overlap width of 0.1 mm or less and overlapping with the sealing
agent when viewed in a vertical direction relative to the substrate
surface.
4. A liquid crystal display device according to claim 1, wherein at
least one of the one substrate and the other substrate includes, on
a surface outside the light shielding film, a light path changing
part for changing a light path of incident light toward the sealing
agent.
5. A liquid crystal display device according to claim 4, wherein
the light path changing part includes irregularities formed before
the sealing agent is irradiated with light.
6. A liquid crystal display device according to claim 4, wherein
the light path changing part includes an optical film bonded before
the sealing agent is irradiated with light.
7. A liquid crystal display device according to claim 6, wherein
the optical film includes a diffusion sheet.
8. A liquid crystal display device according to claim 6, wherein
the optical film includes a prism sheet.
9. A liquid crystal display device according to claim 1, wherein
the one substrate includes, on a surface outside the light
shielding film, an incident light increasing part for increasing
incident light.
10. A liquid crystal display device according to claim 9, the
incident light increasing part includes an optical film bonded
before the sealing agent is irradiated with light.
11. A liquid crystal display device according to claim 10, wherein
the optical film includes an antireflection film.
12. A substrate for a liquid crystal display device, comprising: a
light shielding film formed on a transparent substrate; a sealing
agent coating region disposed on the light shielding film where a
sealing agent is coated when the transparent substrate is bonded to
an opposite substrate disposed to be opposite; a temporary
fastening sealing agent coating region where a temporary fastening
sealing agent is coated when the transparent substrate is bonded to
the opposite substrate disposed to be opposite; and a light
shielding layer disposed around the temporary fastening sealing
agent coating region and for intercepting light so that the light
irradiated to the temporary fastening sealing agent is not
irradiated to the sealing agent.
13. A liquid crystal display device comprising two substrates
disposed to be opposite to each other, and a liquid crystal sealed
between the two substrates, wherein a substrate for a liquid
crystal display device according to claim 12 is used for one of the
two substrates.
14. A manufacturing apparatus of a liquid crystal display device,
comprising: an irradiation stage for mounting a bonded substrate
including two substrates bonded through a photo-curing sealing
agent; a light source for irradiating the bonded substrate with
light to cure the sealing agent; and a reflection mirror for
reflecting the light so that the light is incident on a surface of
the bonded substrate in an inclined direction.
15. A manufacturing apparatus of a liquid crystal display device,
comprising: an irradiation stage having an irradiation surface on
which a bonded substrate including two substrates bonded through a
photo-curing sealing agent is mounted, and provided with one of a
metal layer having a high optical reflectance, a white plate and a
scattering sheet on the irradiation surface; and a light source for
irradiating the bonded substrate with light to cure the sealing
agent.
16. A manufacturing method of a liquid crystal display device,
comprising: a first step of coating a photo-curing sealing agent on
an outer peripheral part of one of a pair of substrates; a second
step of bonding the pair of substrates through the sealing agent to
fabricate a bonded substrate; and a third step of curing the
sealing agent by irradiation of light, wherein the manufacturing
method of the liquid crystal display device further comprises,
before the third step, a step of performing, at least at one of a
front surface and a rear surface of the bonded substrate and at a
region outside the sealing agent coated region, a light path
changing treatment for changing a light path of light incident on
the substrate toward the sealing agent or an incident light
increasing treatment for increasing light incident on the
substrate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a substrate for a liquid
crystal display device used for a display part of an information
equipment, a liquid crystal display device provided with the same,
a manufacturing method of the same, and a manufacturing apparatus
of the same.
[0003] 2. Description of the Related Art
[0004] An active matrix type liquid crystal display device
including a thin film transistor (TFT) as a switching element in
each pixel has attracted attention as the mainstream of a flat
panel display, and it is desired to reduce the cost by the
improvement of manufacturing yield and the reduction of product
defects. An active matrix type color liquid crystal display device
is constituted by a TFT substrate on which TFTs and the like are
formed, a CF substrate on which color filters (CF) and the like are
formed, and a liquid crystal sealed between both the
substrates.
[0005] In a substrate bonding process of a manufacturing process of
a liquid crystal display device, a sealing agent is coated and
formed on an outer peripheral part of one of the TFT substrate and
the CF substrate. Next, both the substrates are superposed on each
other, and a pressure is applied by using a substrate bonding
apparatus such as a pressure-heating apparatus or a vacuum heating
apparatus to bond them, so that a bonded substrate having a
predetermined cell gap is fabricated one by one. Thereafter, in a
liquid crystal injection process, a liquid crystal is injected in
the cell gap of the bonded substrate by using a vacuum injection
method or the like, and a liquid crystal injection port is
sealed.
[0006] However, as a substrate size is enlarged in recent years,
there arises a problem in the vacuum injection method that it is
difficult to form the cell gap with high accuracy, and it takes a
long time to inject the liquid crystal. As a method for solving the
above problem, there is a drop injection method (drop bonding). In
the drop injection method, a sealing agent is coated to have a
frame shape on an outer peripheral part of one substrate, a
predetermined amount of liquid crystal is dropped onto a substrate
surface within the frame, and both the substrates are bonded to
each other in vacuum to seal the liquid crystal. According to the
drop injection method, the bonding of the substrates and the
injection of the liquid crystal can be completed almost
simultaneously, and the manufacturing process is greatly
simplified.
[0007] The manufacturing process of a liquid crystal display panel
according to the drop injection method will be described in brief.
First, a liquid crystal is dropped to plural places on a surface of
one substrate by using a liquid crystal drop injection apparatus.
Next, the one substrate and the other substrate on which a sealing
agent is coated on an outer peripheral part are aligned with each
other, and both the substrates are bonded to fabricate a bonded
substrate. This process is carried out in vacuum. Next, when the
bonded substrate is returned into the air, the liquid crystal in
the bonded substrate is diffused by the atmospheric pressure. Next,
the sealing agent is cured so that the liquid crystal display panel
is completed.
[0008] In the drop injection process using the drop injection
method, since the bonding of the substrates and the injection of
the liquid crystal are performed at the same time, the uncured
sealing agent and the liquid crystal come in contact with each
other. When an uncured component of the sealing agent is in contact
with the liquid crystal for a long time or is exposed to high
temperature in that state, the liquid crystal is contaminated.
Thus, a thermosetting resin is not generally used as the sealing
agent in the case where the drop injection method is used, and a
photo-curing resin quickly cured by ultraviolet light (UV light)
irradiation is used.
[0009] Incidentally, in recent years, as a liquid crystal display
panel is enlarged, it is desired to realize frame narrowing, that
is, to narrow the width of a frame part outside of a display
region. FIG. 11 is a schematic sectional view showing a structural
example in the vicinity of a frame part of a conventional liquid
crystal display device. As shown in FIG. 11, the liquid crystal
display device is constituted by a TFT substrate 102, a CF
substrate 104 and a liquid crystal 114 sealed between both the
substrates 102 and 104. At the CF substrate 104 of a frame part B
outside of a display region A of the liquid crystal display device,
a light shielding film (BM) 108 for intercepting the light is
formed on a glass substrate 107. Besides, at the side of the TFT
substrate 102 of the frame part B, metal wiring lines 110 and 111
such as common storage capacitor lines for bundling plural storage
capacitor bus lines are formed on a glass substrate 106.
[0010] In FIG. 11, a sealing agent (main seal) 112 is coated at a
position where it overlaps with the BM 108 and the metal wiring
lines 110 and 111 when viewed in the direction vertical to the
substrate surface. However, if the sealing agent 112 is coated at
such a position, the light in the vertical direction relative to
the substrate surface is intercepted by the BM and is not
irradiated to the sealing agent 112. Besides, since a width W of
the metal wiring line 111 is very large as compared with a cell gap
d, the intensity of the light in an oblique direction relative to
the substrate surface is also attenuated by multiple reflection
between the BM 108 and the metal wiring line 111, and the light
having an intensity necessary for curing is not irradiated to the
sealing agent 112. Thus, a poor cured region is produced in the
sealing agent 112. Accordingly, in the liquid crystal display
device manufactured by using the drop injection method, it is
necessary to coat the sealing agent 112 on the outside (the right
in the drawing) of the BM 108. Incidentally, with respect to bus
lines or the like formed in a direction almost perpendicular to a
coating direction of the sealing agent 112, since a wiring interval
thereof is wide as compared with a wiring width, they seldom become
a problem.
[0011] However, when the sealing agent 112 is coated on the outside
of the BM 108, there arises a problem that the width of the frame
region B becomes large. For example, when the sealing agent 112 can
be coated to overlap with the BM 108, the width of the frame region
B can be made to substantially coincide with the width of the BM
108. On the other hand, according to the above method, the width of
the frame region B becomes wider by the coating width of the
sealing agent 112.
[0012] Besides, when UV light having a very high intensity is
irradiated to the sealing agent to shorten an irradiation time,
there arises a problem that leakage light is incident on a liquid
crystal 114, and the liquid crystal 114 is contaminated.
SUMMARY OF THE INVENTION
[0013] An object of the invention is to provide a substrate for a
liquid crystal display device in which a manufacturing process can
be simplified and a frame part can be narrowed, a liquid crystal
display device provided with the same, a manufacturing method of
the same, and a manufacturing apparatus of the same.
[0014] The above object is achieved by a liquid crystal display
device characterized by comprising two substrates disposed to be
opposite to each other, a liquid crystal sealed between the two
substrates, a light shielding film formed on an outer peripheral
part of one of the substrates to intercept light, a display region
defined by the light shielding film, a metal layer formed on the
other substrate at a side of the liquid crystal of the outer
peripheral part and having a width of 0.1 mm or less, and a
photo-curing sealing agent coated on the outer peripheral part to
overlap with the light shielding film when viewed in a vertical
direction relative to a substrate surface and provided with a light
irradiated region overlapping with the metal layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a view showing a structure of a liquid crystal
display device according to a first embodiment of the
invention;
[0016] FIG. 2 is a view showing a structure of the liquid crystal
display device according to the first embodiment of the
invention;
[0017] FIG. 3 is a sectional view showing a structure of the liquid
crystal display device according to the first embodiment of the
invention;
[0018] FIG. 4 is a view showing a structure of a manufacturing
apparatus of the liquid crystal display device according to the
first embodiment of the invention;
[0019] FIG. 5 is a sectional view showing a liquid crystal display
device according to a second embodiment of the invention;
[0020] FIG. 6 is a sectional view showing a liquid crystal display
device according to a third embodiment of the invention;
[0021] FIG. 7 is a view showing a manufacturing process of a liquid
crystal display device according to a fourth embodiment of the
invention;
[0022] FIG. 8 is a sectional view showing a structure of a
substrate for a liquid crystal display device according to the
fourth embodiment of the invention;
[0023] FIG. 9 is a sectional view showing a structure of a
substrate for a liquid crystal display device according to a fifth
embodiment of the invention;
[0024] FIG. 10 is a sectional view showing a modified example of
the structure of the substrate for the liquid crystal display
device according to the fifth embodiment of the invention; and
[0025] FIG. 11 is a sectional view showing a structural example of
a conventional liquid crystal display device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] (First Embodiment)
[0027] A liquid crystal display device according to a first
embodiment and a manufacturing apparatus of the same will be
described with reference to FIGS. 1 to 4. FIG. 1 shows a schematic
structure of the liquid crystal display device according to this
embodiment. The liquid crystal display device has such a structure
that a TFT substrate 2 on which TFTs and the like are formed is
made to be opposite to and to be bonded to a CF substrate 4 on
which CFs and the like are formed, and a liquid crystal is sealed
between both the substrates 2 and 4. On the TFT substrate 2, gate
bus lines and storage capacitor bus lines and drain bus lines are
formed to intersect with each other through an insulating film.
[0028] The TFT substrate 2 is provided with a gate bus line driving
circuit 80 on which a driver IC for driving the plural gate bus
lines is mounted and a drain bus line driving circuit 81 on which a
driver IC for driving the plural drain bus lines is mounted. These
driving circuits 80 and 81 output a scanning signal or a data
signal to a predetermined gate bus line or drain bus line on the
basis of a predetermined signal outputted from a control circuit
82. A polarizing plate 83 is disposed on a substrate surface of the
TFT substrate 2 opposite to an element formation surface, and a
back light unit 85 is attached to a reverse surface of the
polarizing plate 83 with respect to the TFT substrate 2. On the
other hand, a polarizing plate 84 disposed in crossed Nicols is
bonded to a surface of the CF substrate 4 opposite to a CF
formation surface.
[0029] FIG. 2 shows a structure in the vicinity of a frame part of
the liquid crystal display device according to this embodiment
viewed from the side of the TFT substrate 2. FIG. 3 is a schematic
sectional view in the vicinity of the frame part of the liquid
crystal display device taken along line A-A of FIG. 2. As shown in
FIGS. 2 and 3, the TFT substrate 2 and the CF substrate 4 are
bonded to each other through a photo-curing sealing agent 16 coated
on an outer peripheral part of one of the substrates 2 and 4.
[0030] At the side of the CF substrate 4, a BM 8 for intercepting
the light is formed on a transparent glass substrate 7. Besides, at
the side of the TFT substrate 2, metal wiring lines 10, 11 and 12
such as, for example, common storage capacitor lines for bundling
plural storage capacitor bus lines (not shown) are formed on a
transparent glass substrate 6. The metal wiring lines 10, 11 and 12
are formed, for example, in parallel with a coating direction of
the sealing agent 16. A width W1 of the metal wiring line 10, a
width W2 of the metal wiring line 11 and a width W3 of the metal
wiring line 12 are all 0.1 mm or less.
[0031] When the widths of the metal wiring lines 10, 11 and 12 are
made 0.1 mm or less, it has been found from experiments that light
of multiple reflection between the BM 8 and the metal wiring lines
10, 11 and 12 can be irradiated to regions of the sealing agent 16
where it overlaps with the metal wiring lines 10, 11 and 12.
[0032] Although described later in detail, according to this
structure, light beams a and b obliquely incident on a substrate
surface are reflected at a rear surface of the glass substrate 6
and the metal wiring lines 10, 11 and 12, so that the light having
an intensity necessary for photo-curing is irradiated to the whole
region of the sealing agent 16. Hereinafter, a sealing agent region
to which the light having the intensity necessary for photo-curing
is irradiated is called a light irradiated region. In this
embodiment, as described above and as shown in FIG. 3, the light
irradiated region 40 is the whole region of the sealing agent
16.
[0033] Next, a manufacturing method of the liquid crystal display
device according to this embodiment will be described. First, the
TFT substrate 2 and the CF substrate 4 are manufactured in
respective processes. Next, for example, a predetermined amount of
liquid crystal is dropped onto plural places of a surface of the
TFT substrate 2, and the sealing agent 16 is coated on the outer
peripheral part of the CF substrate 4. Next, both the substrates 2
and 4 are aligned with each other and are bonded in vacuum by using
a substrate bonding apparatus to fabricate a bonded substrate.
Next, when the bonded substrate is returned into the air, the
liquid crystal in the bonded substrate is diffused by the
atmospheric pressure.
[0034] Next, UV light is irradiated to the sealing agent 16 by
using a UV light irradiation apparatus. As shown in FIG. 3, the
light beams a and b incident on the glass substrate 7 in an
inclined direction relative to the substrate surface are
transmitted through the glass substrate 7 and are incident on the
glass substrate 6. The light beams a and b are reflected at the
rear surface (lower part in the drawing) of the glass substrate 6
or a surface of an irradiation stage (not shown in FIG. 3) being in
contact with the rear surface of the glass substrate 6, and are
incident on the sealing agent 16. Thereafter, the light beams a and
b are further reflected at surfaces of the metal wiring lines 10,
11 and 12, and are also incident on regions of the sealing agent 16
where the metal wiring lines 10, 11 and 12 are formed to overlap.
By this, the UV light is irradiated on all the regions of the
sealing agent 16, and the sealing agent 16 is quickly cured. The
liquid crystal display device is completed through the above
processes.
[0035] Next, a manufacturing apparatus of the liquid crystal
display device according to this embodiment will be described with
reference to FIG. 4. FIG. 4 shows a schematic structure of a UV
light irradiation apparatus 20 used for the manufacture of the
liquid crystal display device according to this embodiment. As
shown in FIG. 4, the UV light irradiation apparatus 20 includes an
irradiation stage 22 for mounting thereon a bonded substrate 30 in
which a liquid crystal 14 is injected by using a drop injection
method and the photo-curing sealing agent 16 is coated on the outer
peripheral part. A UV light source 24 for irradiating UV light is
disposed above the irradiation stage 22. Besides, at sides of the
irradiation stage 22, reflection mirrors 26 are disposed which
reflect the UV light from the UV light source 24 so that the light
is incident on the surface of the bonded substrate 30 in an
inclined direction. The reflection mirrors 26 are provided, for
example, at four sides of the irradiation stage 22,
respectively.
[0036] In the UV light irradiation apparatus 20, the UV light not
irradiated to the bonded substrate 30 can be reflected by the
reflection mirrors 26 in the direction toward the bonded substrate
30. Thus, the use efficiency of the UV light is improved. Besides,
an incident angle of the UV light incident on the bonded substrate
30 becomes large, so that a component of the UV light in a
substrate surface direction is increased, and therefore, the number
of times of reflection of the UV light is decreased.
[0037] The irradiation stage 22 includes, for example, a metal
layer having a high optical reflectance or a white plate on the
surface (irradiated surface). By this, the light from the UV light
source 24 can be efficiently irradiated to the sealing agent 16.
The irradiation stage 22 may include thereon a scattering sheet for
scattering and reflecting the light.
[0038] As stated above, according to this embodiment, even when the
photo-curing sealing agent 16 is coated to overlap with the BM 8,
the sealing agent 16 can be cured. Thus, even if the drop injection
method is used for the manufacture, it is possible to realize the
liquid crystal display device in which the frame part can be
narrowed.
[0039] (Second Embodiment)
[0040] Next, a liquid crystal display device according to a second
embodiment of the invention will be described with reference to
FIG. 5. FIG. 5 shows a schematic sectional structure in the
vicinity of a frame part of the liquid crystal display device
according to this embodiment. As shown in FIG. 5, metal wiring
lines 41 and 42 are formed on a glass substrate 6 of a TFT
substrate 2 substantially in parallel with a coating direction of a
sealing agent 16, for example. The width of the metal wiring line
41 formed outside is larger than 0.1 mm and the width of the metal
wiring line 42 formed inside is 0.1 mm or less.
[0041] As described in the first embodiment, when the width of the
metal wiring line is 0.1 mm or less, light by multiple reflection
between the BM and the metal wiring line can be irradiated to a
sealing agent region overlapping with the metal wiring line. On the
other hand, when the width of the metal wiring line exceeds 0.1 mm,
there is a possibility that light necessary for curing can not be
irradiated to a sealing agent region on the metal wiring line.
Accordingly, in the sealing agent 16 according to this embodiment,
a light irradiated region 40 is positioned in an end part at the
side of a liquid crystal 14.
[0042] Next, a manufacturing method of the liquid crystal display
device according to this embodiment will be described. Similarly to
the first embodiment, a bonded substrate 30 is mounted on the
irradiation stage 22 of the UV light irradiation apparatus 20 and
UV light is irradiated. As shown in FIG. 5, light beams c and d
incident on the glass substrate 7 in an inclined direction relative
to the substrate surface are transmitted through the glass
substrate 7 and are incident on the glass substrate 6. The light
beam c is reflected at the rear surface of the glass substrate 6 or
the surface of the irradiation stage 22 and is incident on the
light irradiated region 40 of the sealing agent 16. Besides, the
light beam d is reflected at the rear surface of the glass
substrate 6 or the surface of the irradiation stage 22, and is
further reflected at the rear surface of the metal wiring line 41.
The light beam d is again reflected at the rear surface of the
glass substrate 6 or the surface of the irradiation stage 22, and
is incident on the light irradiated region 40 of the sealing agent
16. The light beam d is further reflected at the BM 8 and the metal
wiring line 42, and is also incident on a region of the light
irradiated region 40 of the sealing agent 16 where the metal wiring
line 42 is formed to overlap.
[0043] The thickness of the glass substrate 6 is very large as
compared with a cell gap. Thus, the number of times of reflection
until the UV light reaches the light irradiated region 40 of the
sealing agent 16 is relatively small, and the attenuation of
intensity of the UV light is small. By this, the UV light having an
intensity necessary for curing is irradiated to the whole light
irradiated region 40 of the sealing agent 16, and the light
irradiated region 40 of the sealing agent 16 is quickly cured.
Thus, liquid crystal contamination does not occur.
[0044] Incidentally, since the sealing agent 16 in a region where
it is formed to overlap with the metal wiring line 41 is hardly
cured, there is a case where the adhesion strength between both the
substrates 2 and 4 is not sufficient. In this case, a thermosetting
sealing agent is previously mixed, and for example, secondary
curing may be performed in which the bonded substrate 30 is heated
to cure the uncured sealing agent 16.
[0045] Besides, if the width of the light irradiated region 40 is
extremely small, the light leaks toward the side of the liquid
crystal, and liquid crystal contamination occurs. Thus, it is
necessary to determine the width of the light irradiated region 40
by mutual relation among material property values, various
conditions of the manufacturing process and the like.
[0046] (Third Embodiment)
[0047] Next, a liquid crystal display device according to a third
embodiment of the invention will be described with reference to
FIG. 6. FIG. 6 shows a schematic sectional structure in the
vicinity of a frame part of the liquid crystal display device
according to this embodiment. As shown in FIG. 6, on a glass
substrate 6 of a TFT substrate 2, a light shielding layer 50 made
of a metal layer such as, for example, a gate bus line formation
layer or a drain bus line formation layer is formed within a range
from an end part of a sealing agent 16 at a side of a liquid
crystal 14 to an outside of a display region. The light shielding
layer 50 is provided to prevent contamination of the liquid crystal
14 due to UV light transmitted through the sealing agent 16 and
incident on the liquid crystal 14. The light shielding layer 50
includes an overlap region 44 overlapping with the sealing agent 16
and having an overlap width of 0.1 mm or less when viewed in a
vertical direction relative to a substrate surface.
[0048] As shown in FIG. 6, light beams e and f incident on a glass
substrate 7 in an inclined direction relative to the substrate
surface are transmitted through the glass substrate 7 and are
incident on the glass substrate 6. The light beam e is reflected at
the rear surface of the glass substrate 6 or the surface of the
irradiation stage 22, and is further reflected at the surface of a
BM 8. The light beam e is again reflected at the rear surface of
the glass substrate 6 or the surface of the irradiation stage 22
and advances to the liquid crystal 14 of the frame part. However,
the light beam is reflected at the light shielding layer 50. As
stated above, the light shielding layer 50 increases the number of
times of reflection of the UV light, and attenuates the intensity
of the UV light to the utmost.
[0049] The light beam f incident on the glass substrate 6 is
reflected at the rear surface of the glass substrate 6 or the
surface of the irradiation stage 22, and is further reflected at
the rear surface of the metal wiring line 41. The light beam f is
again reflected at the rear surface of the glass substrate 6 or the
surface of the irradiation stage 22, and is reflected at the
surface of the BM 8. Thereafter, the light beam is subjected to
multiple reflection between the surface of the light shielding
layer 50 and the surface of the BM 8, and the intensity is
attenuated. Thus, when the UV light is incident on the liquid
crystal 14, the intensity is sufficiently lowered.
[0050] According to this embodiment, since the UV light having a
high intensity is not incident on the liquid crystal 14, the liquid
crystal 14 is not contaminated. Thus, the liquid crystal display
device having excellent display quality can be obtained.
[0051] (Fourth Embodiment)
[0052] Next, a substrate for a liquid crystal display device
according to a fourth embodiment and a liquid crystal display
device provided with the same will be described with reference to
FIGS. 7 and 8. First, a manufacturing process of a liquid crystal
display device as the premise of this embodiment will be described.
FIG. 7 is a view for explaining the manufacturing process of the
liquid crystal display device according to this embodiment, and
shows a multiple (for example, four-face) bonded substrate 68. The
bonded substrate 68 is constructed such that for example, a TFT
substrate 2 on which a liquid crystal 14 is dropped is bonded to a
CF substrate 4 in which a sealing agent 16 is coated on an outer
peripheral part of each liquid crystal display panel 70. Besides,
temporary fastening sealing agents 60 each having, for example, a
circular shape with a diameter of 1 to 2 mm are coated on, for
example, four corners of the bonded substrate 68.
[0053] Alignment of the TFT substrate 2 and the CF substrate 4 is
performed with predetermined bonding accuracy by using a substrate
bonding apparatus, and immediately after that, the temporary
fastening sealing agents 60 are locally irradiated with the UV
light and are cured. The temporary fastening sealing agents 60 are
cured to have such strength that for example, when it is
transported from the substrate bonding apparatus to a UV light
irradiation apparatus, a position shift does not occur between both
the substrates 2 and 4. However, at this time of point, since the
accuracy of a cell gap and the diffusion of the liquid crystal 14
are insufficient, if the sealing agent (main seal) 16 is also
cured, product defects are produced.
[0054] FIG. 8 is a sectional view showing a schematic structure of
the substrate for the liquid crystal display device according to
this embodiment. As shown in FIG. 8, the CF substrate 4 includes a
light shielding layer 62 made of, for example, a metal layer in the
vicinity of a temporary fastening sealing agent coating region
where the temporary fastening sealing agent 60 is coated. The light
shielding layer 62 intercepts the light so that leakage light of UV
light irradiated to the temporary fastening sealing agent 60 from a
UV light source 24 is not irradiated to the sealing agent 16.
[0055] Incidentally, the temporary fastening sealing agent 60 and
the light shielding layer 62 may be cut off and discarded in a
process before the liquid crystal display device is completed.
[0056] According to this embodiment, when the temporary fastening
sealing agents 60 are cured, the sealing agent 16 is not cured, and
therefore, product defects of the liquid crystal display device are
decreased.
[0057] (Fifth Embodiment)
[0058] Next, a liquid crystal display device according to a fifth
embodiment of the invention and a manufacturing method of the same
will be described with reference to FIGS. 9 and 10. FIG. 9 is a
sectional view schematically showing a structure in the vicinity of
a frame part of the liquid crystal display device according to this
embodiment. As shown in FIG. 9, on a surface of a glass substrate 7
of a CF substrate 4 at the outside of a panel (upper part in the
drawing), for example, embossed minute irregularities 72 are formed
as a light path changing part for changing a light path. The
irregularities 72 are formed at least in a region outside of a BM
8. Besides, the irregularities 72 are formed before a step of
curing a sealing agent 16 by irradiation of UV light to fabricate a
bonded substrate.
[0059] Next, a manufacturing method of the liquid crystal display
device according to this embodiment will be described. First, a TFT
substrate 2 and a CF substrate 4 are manufactured by a
predetermined process. Next, a light path changing treatment is
performed in which for example, the embossed minute irregularities
72 are formed at a rear surface side of the CF substrate 4 with
respect to a formation surface with the BM 8 and at at least a part
outside of the BM 8. Next, a predetermined amount of liquid crystal
14 is dropped onto, for example, plural places of a surface of the
TFT substrate 2, and a sealing agent 16 is coated on an outer
peripheral part of the CF substrate 4. Next, both the substrates 2
and 4 are aligned and bonded to each other in vacuum by using a
substrate bonding apparatus, so that a bonded substrate is
fabricated. Next, when the bonded substrate is returned into the
air, the liquid crystal 14 in the bonded substrate is diffused by
the atmospheric pressure. Incidentally, the irregularities 72 may
be formed at other timings before a step of curing the sealing
agent 16 by irradiation of UV light described later, for example,
it may be formed before CFs are formed on the glass substrate 7 or
after the bonded substrate is fabricated.
[0060] Next, the UV light is irradiated to the sealing agent 16 by
using a UV light irradiation apparatus. As shown in FIG. 9, light
beams g and h incident on the glass substrate 7 in a direction
relatively close to a vertical direction relative to a substrate
surface after formation of the irregularities 72 (hereinafter
simply referred to as "substrate surface") are incident on one
inclined surface of the irregularities 72. The light beam g
incident on the inclined surface inclined so that the outside (the
right in the drawing) of the glass substrate 7 becomes low is
refracted into a light beam g'. Similarly, the light beam h
incident on the inclined surface inclined so that the outside of
the glass substrate 7 becomes low is refracted into a light beam
h'. The light path of the light beam g' is changed toward the side
of the sealing agent 16 with respect to the light beam g, and the
light path of the light beam h' is changed toward the side of the
sealing agent 16 with respect to the light beam h. The light beams
g' and h' have light paths changed in directions closer to a
direction parallel to the substrate surface.
[0061] The light beams g' and h' are transmitted through the glass
substrate 7 and are incident on the glass substrate 6. The light
beams g' and h' are reflected at the rear surface (panel outside
surface) of the glass substrate 6 or the surface of an irradiation
stage (not shown in FIG. 9) being in contact with the rear surface
of the glass substrate 6, and are incident on the sealing agent 16.
Thereafter, the light beams g' and h' are further reflected at the
surfaces of the metal wiring lines 10, 11 and 12, and are also
incident on regions of the sealing agent 16 where the metal wiring
lines 10, 11 and 12 are formed to overlap. By this, the UV light is
irradiated on all the regions of the sealing agent 16, and the
sealing agent 16 is quickly cured. Thereafter, part of the
substrates 2 and 4 outside the sealing agent 16 may be cut of f and
discarded. The liquid crystal display device according to this
embodiment is completed through the above processes.
[0062] In this embodiment, although the irregularities 72 are
formed to have the embossed shape, the irregularities 72 may be
formed to have a prism shape for changing the light path of light
incident on the glass substrate 7 toward the side of the sealing
agent 16. Besides, in addition to that, the irregularities 72 may
be formed to have another shape as long as a light path of at least
a part of light can be changed toward the side of the sealing agent
16 by scattering or refracting the incident light. Further, in this
embodiment, although the irregularities 72 are formed on the panel
outside surface of the CF substrate 4, the irregularities 72 may be
formed on the panel outside surface (the lower part in the drawing)
of the TFT substrate 2.
[0063] Besides, if the irregularities 72 are so minute that the
display quality does not deteriorate, they may be formed in a
display region. If the minute irregularities 72 are formed in the
whole display region of the panel outside surface of the CF
substrate 4, they serve as a diffusion sheet for preventing surface
reflection, and therefore, there is also an effect that bonding of
the diffusion sheet onto the surface of the glass substrate 7
becomes unnecessary.
[0064] According to this embodiment, the light path of light
incident on the glass substrate 7 in a direction relatively close
to the vertical direction relative to the substrate surface can be
changed toward the side of the sealing agent 16. In general, when
light is irradiated by using a UV irradiation apparatus, since
luminous energy of the light incident on the glass substrate 7 in
the direction relatively close to the vertical direction relative
to the substrate surface is large, it becomes possible to irradiate
the sealing agent 16 with the light having more luminous energy.
Accordingly, even if the photo-curing sealing agent 16 is coated to
overlap with the BM 8, the sealing agent 16 can be more quickly
cured. Thus, even if the drop injection method is used for
manufacture, it is possible to realize the liquid crystal display
device in which the frame part can be narrowed.
[0065] Next, a modified example of the liquid crystal display
device according to this embodiment and the manufacturing method of
the same will be described. FIG. 10 shows a structure of a liquid
crystal display device according to this modified example. As shown
in FIG. 10, a diffusion sheet 74 of an optical film is bonded, as a
light path changing part for changing the light path of light, to a
surface of a glass substrate 7 of a CF substrate 4 at the panel
outside (the upper part in the drawing). The diffusion sheet 74 is
bonded to at least a region outside a BM 8. Besides, the diffusion
sheet 74 is bonded before a step of curing a sealing agent 16 by
irradiation of UV light to fabricate a bonded substrate.
[0066] Next, a manufacturing method of the liquid crystal display
device according to this modified example will be described. First,
a TFT substrate 2 and a CF substrate 4 are manufactured by a
predetermined process. Next, a light path changing treatment is
performed in which the diffusion sheet 74, which is generally
bonded after a bonded substrate is fabricated, is bonded to
substantially the whole surface (at least a part outside the BM 8)
of the rear surface side of the CF substrate 4 with respect to the
formation surface with the BM 8. Next, for example, a predetermined
amount of liquid crystal 14 is dropped onto plural places of the
surface of the TFT substrate 2, and the sealing agent 16 is coated
on the outer peripheral part of the CF substrate 4. Next, both the
substrates 2 and 4 are aligned and bonded to each other in vacuum
by using a substrate bonding apparatus, and a bonded substrate is
fabricated. Next, when the bonded substrate is returned into the
air, the liquid crystal 14 in the bonded substrate is diffused by
the atmospheric pressure. Incidentally, the diffusion sheet 74 may
be bonded at other timings before a step of curing the sealing
agent 16 by irradiation of UV light, for example, it may be bonded
before CFs are formed on the glass substrate 7 or after the bonded
substrate is fabricated.
[0067] Next, the UV light is irradiated to the sealing agent 16 by
using a UV light irradiation apparatus. As shown in FIG. 10, light
beams i and j incident on the glass substrate 7 in a direction
relatively close to the vertical direction relative to the
substrate surface are incident on the diffusion sheet 74. The light
beam i is diffused by the diffusion sheet 74, and a part thereof is
transmitted as a light beam k. The light beam j is diffused by the
diffusion sheet 74, and a part thereof is transmitted as a light
beam 1. The light path of the light beam k is changed toward the
side of the sealing agent 16 with respect to the light beam i, and
the light path of the light beam 1 is changed toward the side of
the sealing agent 16 with respect to the light beam j. The light
beams k and 1 have light paths changed toward directions closer to
the direction parallel to the substrate surface.
[0068] The light beams k and 1 are transmitted through the glass
substrate 7 and are incident on the glass substrate 6. The light
beams k and 1 are reflected at the rear surface (panel outside
surface) of the glass substrate 6 or the surface of an irradiation
stage (not shown in FIG. 10) being in contact with the rear surface
of the glass substrate 6, and are incident on the sealing agent 16.
Thereafter, the light beams k and 1 are further reflected at the
surfaces of the metal wiring lines 10, 11 and 12, and are also
incident on regions of the sealing agent 16 where the metal wiring
lines 10, 11 and 12 are formed to overlap. By this, the UV light is
irradiated on all the regions of the sealing agent 16, and the
sealing agent 16 is quickly cured. Thereafter, part of the
substrates 2 and 4 outside of the sealing agent 16 may be cut off
and discarded. The liquid crystal display device according to this
modified example is completed through the above processes.
[0069] In this example, although the diffusion sheet 74 as the
light path changing part is bonded to the panel outside surface of
the CF substrate 4, the diffusion sheet 74 may be bonded to the
panel outside surface of the TFT substrate 2. Besides, in this
example, although the diffusion sheet 74 is bonded as an optical
film, another optical film, such as a prism sheet, capable of
changing a light path of at least part of light toward the side of
the sealing agent 16 may be bonded. Alternatively, instead of the
light path changing treatment for forming the light path changing
part, an incident light increasing treatment may be performed in
which an optical film such as an antireflection (AR) film is bonded
to the panel outside surface of the CF substrate 4 as an incident
light increasing part for increasing the luminous energy of light
incident on the glass substrate 7 by increasing the transmissivity
of incident light. Further, plural such optical films may be
stacked and bonded. Besides, the optical film may have a function
as a polarizing plate.
[0070] In this example, although the optical film such as the
diffusion sheet 74 is bonded to substantially the whole surface
including the display region, it may be bonded to only a region
outside of the BM 8. In this case, it becomes necessary to provide
a step of bonding another optical film to the display region and
its periphery after the bonded substrate is fabricated.
[0071] According to this modified example, since it becomes
unnecessary to provide a step of forming the irregularities 72 on
the panel outside surface of the TFT substrate 2 or the CF
substrate 4, the manufacturing process of the liquid crystal
display device can be simplified.
[0072] In the invention, various modifications can be made in
addition to the above embodiments.
[0073] For example, in the above-mentioned embodiments, although
the metal wiring lines are formed in parallel with a coating
direction of the sealing agent, the invention is not limited to
this. The metal wiring lines can also be formed not in parallel
with the coating direction of the sealing agent. Besides, while the
metal wiring lines are crossed on the substrate, the maximum widths
of the metal wiring lines are all 0.1 mm or less. Therefore, the
maximum widths of crossed portion of the wiring lines are also all
0.1 mm or less.
[0074] For example, in the first, second to fifth embodiments,
although the liquid crystal display device is cited as an example
in which the liquid crystal is injected using the drop injection
method, the invention is not limited to this, but can be applied to
a liquid crystal display device in which the liquid crystal is
injected using a vacuum injection method.
[0075] Besides, in the above embodiments, although the UV light is
irradiated from the side of the CF substrate 4, the invention is
not limited to this. For example, in the case of a CF-on-TFT
structure in which a color filter is formed on the side of the TFT
substrate 2, the UV light can also be irradiated from the side of
the TFT substrate 2. Besides, when a mask for shading the display
region is used, the UV light may be irradiated from the side of the
TFT substrate 2 on which CFs are not formed.
[0076] Besides, in the above embodiments, although the transmission
type liquid crystal display device has been exemplified, the
invention is not limited to this, but can also be applied to
another liquid crystal display device such as a reflection type or
a semi-transmission type.
[0077] As described above, according to the invention, it is
possible to realize the substrate for the liquid crystal display
device in which the manufacturing process can be simplified and the
frame part can be narrowed, the liquid crystal display device
provided with the same, the manufacturing method of the same, and
the manufacturing apparatus of the same.
* * * * *